/*******************************************************************************
 * Copyright (c) 2015, 2016 EclipseSource.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/
package com.blade.kit.json;

import java.io.IOException;
import java.io.Reader;

/**
 * This class serves as the entry point to the minimal-json API.
 * <p>
 * To <strong>parse</strong> a given JSON input, use the <code>parse()</code>
 * methods like in this example:
 * </p>
 * 
 * <pre>
 * JsonObject object = Json.parse(string).asObject();
 * </pre>
 * <p>
 * To <strong>create</strong> a JSON data structure to be serialized, use the
 * methods <code>value()</code>, <code>array()</code>, and <code>object()</code>
 * . For example, the following snippet will produce the JSON string
 * <em>{"foo": 23, "bar": true}</em>:
 * </p>
 * 
 * <pre>
 * String string = Json.object().add("foo", 23).add("bar", true).toString();
 * </pre>
 * <p>
 * To create a JSON array from a given Java array, you can use one of the
 * <code>array()</code> methods with varargs parameters:
 * </p>
 * 
 * <pre>
 * String[] names = ...
 * JsonArray array = Json.array(names);
 * </pre>
 */
public final class JSON {

	private JSON() {
		// not meant to be instantiated
	}

	/**
	 * Represents the JSON literal <code>null</code>.
	 */
	public static final JSONValue NULL = new JSONLiteral("null");

	/**
	 * Represents the JSON literal <code>true</code>.
	 */
	public static final JSONValue TRUE = new JSONLiteral("true");

	/**
	 * Represents the JSON literal <code>false</code>.
	 */
	public static final JSONValue FALSE = new JSONLiteral("false");

	/**
	 * Returns a JsonValue instance that represents the given <code>int</code>
	 * value.
	 *
	 * @param value
	 *            the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JSONValue value(Integer value) {
		return new JSONNumber(Integer.toString(value, 10));
	}
	
	public static JSONValue value(Object value) {
		return JSONHelper.toJSONValue(value);
	}
	
	/**
	 * Returns a JsonValue instance that represents the given <code>long</code>
	 * value.
	 *
	 * @param value
	 *            the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JSONValue value(Long value) {
		return new JSONNumber(Long.toString(value, 10));
	}
	
	public static JSONValue value(Byte value) {
		return new JSONNumber(Byte.toString(value));
	}

	/**
	 * Returns a JsonValue instance that represents the given <code>float</code>
	 * value.
	 *
	 * @param value
	 *            the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JSONValue value(Float value) {
		if (Float.isInfinite(value) || Float.isNaN(value)) {
			throw new IllegalArgumentException("Infinite and NaN values not permitted in JSON");
		}
		return new JSONNumber(cutOffPointZero(Float.toString(value)));
	}

	/**
	 * Returns a JsonValue instance that represents the given
	 * <code>double</code> value.
	 *
	 * @param value
	 *            the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JSONValue value(Double value) {
		if (Double.isInfinite(value) || Double.isNaN(value)) {
			throw new IllegalArgumentException("Infinite and NaN values not permitted in JSON");
		}
		return new JSONNumber(cutOffPointZero(Double.toString(value)));
	}

	/**
	 * Returns a JsonValue instance that represents the given string.
	 *
	 * @param string
	 *            the string to get a JSON representation for
	 * @return a JSON value that represents the given string
	 */
	public static JSONValue value(String string) {
		return string == null ? NULL : new JSONString(string);
	}

	/**
	 * Returns a JsonValue instance that represents the given
	 * <code>boolean</code> value.
	 *
	 * @param value
	 *            the value to get a JSON representation for
	 * @return a JSON value that represents the given value
	 */
	public static JSONValue value(Boolean value) {
		return value ? TRUE : FALSE;
	}

	/**
	 * Creates a new empty JsonArray. This is equivalent to creating a new
	 * JsonArray using the constructor.
	 *
	 * @return a new empty JSON array
	 */
	public static JSONValue array() {
		return new JSONArray();
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given <code>int</code> values.
	 *
	 * @param values
	 *            the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JSONArray array(Integer... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (int value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given <code>long</code> values.
	 *
	 * @param values
	 *            the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JSONArray array(Long... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (long value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given <code>float</code> values.
	 *
	 * @param values
	 *            the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JSONArray array(Float... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (float value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given <code>double</code> values.
	 *
	 * @param values
	 *            the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JSONArray array(Double... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (double value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given <code>boolean</code> values.
	 *
	 * @param values
	 *            the values to be included in the new JSON array
	 * @return a new JSON array that contains the given values
	 */
	public static JSONArray array(Boolean... values) {
		if (values == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (boolean value : values) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new JsonArray that contains the JSON representations of the
	 * given strings.
	 *
	 * @param strings
	 *            the strings to be included in the new JSON array
	 * @return a new JSON array that contains the given strings
	 */
	public static JSONArray array(String... strings) {
		if (strings == null) {
			throw new NullPointerException("values is null");
		}
		JSONArray array = new JSONArray();
		for (String value : strings) {
			array.add(value);
		}
		return array;
	}

	/**
	 * Creates a new empty JsonObject. This is equivalent to creating a new
	 * JsonObject using the constructor.
	 *
	 * @return a new empty JSON object
	 */
	public static JSONObject create() {
		return new JSONObject();
	}

	/**
	 * Parses the given input string as JSON. The input must contain a valid
	 * JSON value, optionally padded with whitespace.
	 *
	 * @param string
	 *            the input string, must be valid JSON
	 * @return a value that represents the parsed JSON
	 * @throws ParseException
	 *             if the input is not valid JSON
	 */
	public static JSONValue parse(String string) {
		if (string == null) {
			throw new NullPointerException("string is null");
		}
		DefaultHandler handler = new DefaultHandler();
		new JSONParser(handler).parse(string);
		return handler.getValue();
	}

	/**
	 * Reads the entire input from the given reader and parses it as JSON. The
	 * input must contain a valid JSON value, optionally padded with whitespace.
	 * <p>
	 * Characters are read in chunks into an input buffer. Hence, wrapping a
	 * reader in an additional <code>BufferedReader</code> likely won't improve
	 * reading performance.
	 * </p>
	 *
	 * @param reader
	 *            the reader to read the JSON value from
	 * @return a value that represents the parsed JSON
	 * @throws IOException
	 *             if an I/O error occurs in the reader
	 * @throws ParseException
	 *             if the input is not valid JSON
	 */
	public static JSONValue parse(Reader reader) throws IOException {
		if (reader == null) {
			throw new NullPointerException("reader is null");
		}
		DefaultHandler handler = new DefaultHandler();
		new JSONParser(handler).parse(reader);
		return handler.getValue();
	}

	private static String cutOffPointZero(String string) {
		if (string.endsWith(".0")) {
			return string.substring(0, string.length() - 2);
		}
		return string;
	}

	static class DefaultHandler extends JSONHandler<JSONArray, JSONObject> {

		protected JSONValue value;

		@Override
		public JSONArray startArray() {
			return new JSONArray();
		}

		@Override
		public JSONObject startObject() {
			return new JSONObject();
		}

		@Override
		public void endNull() {
			value = NULL;
		}

		@Override
		public void endBoolean(boolean bool) {
			value = bool ? TRUE : FALSE;
		}

		@Override
		public void endString(String string) {
			value = new JSONString(string);
		}

		@Override
		public void endNumber(String string) {
			value = new JSONNumber(string);
		}

		@Override
		public void endArray(JSONArray array) {
			value = array;
		}

		@Override
		public void endObject(JSONObject object) {
			value = object;
		}

		@Override
		public void endArrayValue(JSONArray array) {
			array.add(value);
		}

		@Override
		public void endObjectValue(JSONObject object, String name) {
			object.put(name, value);
		}

		JSONValue getValue() {
			return value;
		}

	}

}
